Benign
breast disorders account for most breast problems. These conditions are
frequently considered in the context of excluding breast cancer and
often are not recognized for their own associated morbidity. To provide
appropriate management, it is important to consider benign breast
disorders from four aspects: (i) clinical picture, (ii) medical significance,(iii) treatment intervention, (iv) and pathologic etiology

A
framework to understand benign breast problems is called Aberrations of
Normal Development and Involution (ANDI). It includes
symptoms,
histology, endocrine state, and pathogenesis in a progression from a
normal to a disease state. Most benign breast conditions arise from
normal changes in breast development, hormone cycling, and reproductive
evolution. Three life cycles reflect different reproductive phases in a
woman's life and are associated with unique breast manifestations.

During
the early reproductive period (15–25 years), lobule and stromal
formation occurs. The ANDI conditions associated with this period are
fibroadenoma (mass) and juvenile hypertrophy (excessive breast
development). In this first stage, the progression from ANDI to a
disease state results in the formation of giant fibroadenomas and
multiple fibroadenomas.

During
the mature reproductive period (25.40 years), cyclic hormonal changes
affect glandular tissue and stroma. In this second period, the ANDI is
an exaggeration of these cyclic effects, such as cyclic mastalgia and
generalized nodularity.

The
third phase is involution of lobules and ducts or turnover of
epithelia, which occurs during ages 35 to 55 years. The ANDI associated
with lobular involution are macrocysts (lumps) and sclerosing lesions
(mammographic abnormalities). Those associated with ductal involution
are duct dilation (nipple discharge) and periductal fibrosis (nipple
retraction), and those with epithelial turnover are mild hyperplasia
(pathologic description).

ABC
of Breast Diseases: Congenital Problems and Aberrations of Normal
Breast Development and Involution

The
breast is identical in boys and girls until puberty. Growth begins at
about the age of 10 and may initially be asymmetrical: a unilateral
breast lump in a 9-10 year old girl is invariably developing breast,
and biopsy specimens should not be taken from girls of this age as they
can damage the breast bud. The functional unit of the breast is the
terminal duct lobular unit or lobule, which drains via a branching duct
system to the nipple. The duct system does not run in a truly radial
manner, and the breast is not separated into easily defined segments.
The lobules and ducts - the glandular tissue - are supported by fibrous
tissue - the stroma. (BMJ
1994;309:797, published 24 September 1994)